IS 15382 (Part 4) :2003 IEC 60664-4 (1997) (Superseding SP 39: 1987) mm R+kea-T * + Wtwii" w ragat?$i T1--TmFf Indian Standard INSULATION COORDINATION FOR EQUIPMENT WITHIN LOW-VOLTAGE SYSTEMS PART 4 CONSIDERATIONS OF HIGH-FREQUENCY VOLTAGE STRESS ICS 29.080.30 @ BIS 2003 BUREAU MANAK OF BHAVAN, INDIAN STANDARDS ZAFAR MARG 9 BAHADUR SHAH NEW DELHI 110002 September 2003 Price Group 10 High Voltage Engineering Sectional Committee, ET 19 NATIONAL FOREWORD This Indian Standard (Part 4) which is identical with IEC 60664-4 (1997) `Insulation coordination for of high-frequency voltage stress' equipment within low-voltage systems -- Part 4: Considerations issued by the International Electrotechnical Commission (lEC) was adopted by the Bureau of Indian Standards on the recommendations of the High Voltage Engineering Sectional Committee and approval of the Electrotechnical Division Council. This standard was first published in 1987 as SP 39 `Special publication -- Guide for insulation coordination within low voltage systems'. The revision of this special publication was felt with a view to align our standard with international practices. This standard consists of the following parts under the general title `Insulation coordination within low voltage systems': Part 1 Part 2 Part 3 Part 4 This standard Principles, Application examples requirements and tests procedure worksheets and dimensioning for equipment guide, Section 1 Dimensioning Use"of coatings to achieve insulation Consideration of high frequency coordination of printed board assemblies voltage-stress is to be read in conduction with Part 1 of this standard. The text of the IEC Standard has been approved as suitable for publication as an Indian Standard without deviations. Certain conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following: a) Wherever the words `International read as `Indian Standard'; and Standard' appear referring to this standard, they should be b) Comma (,) has been used as a decimal marker, while in Indian Standards is to use a point (.) as the decimal marker. of this standard SP 39 shall be withdrawn. Standard has been retained the current practice With the publication Only the English text of the International Standard. CROSS REFERENCES while adopting it as an Indian In this adopted standard, references appear to certain International Standards for which Indian Standards also exist. The corresponding Indian Standards, which are to be substituted in their respective places are listed below along with their degree of equivalence for the editions indicated: International Standard Indian Standard Degree of Equivalence Technically equivalent IEC 60112 (1979) Method for determining the comparative and the proof tracking indices of solid insulating materials under moist conditions lEC 60664-1 (2002) Insulation coordination for equipment within low voltage systems -- Part 1: Principles, requirements and tests IS 2824: 1975 Method for determining the comparative tracking index of solid insulating materials under moist conditions (first revision) IS 15382 (Part 1) : 2003/lEC 60664-1 (2002) Insulation coordination for equipment within low-voltage systems: Part 1 Principles, requirements and tests (Continued Identical on third cover) IS 15382 (Part4) :2003 IEC 60664-4 ( 1997) /ndian Standard INSULATION COORDINATION FOR EQUIPMENT WITHIN LOW-VOLTAGE SYSTEMS PART 4 1 CONSIDERATIONS OF HIGH-FREQUENCY VOLTAGE STRESS Scope deals with insulation subjected to high-frequency voltage stress within Steady-state voltages with frequencies up to 100 MHz are considered. stress due to transient voltages is not considered. This report equipment. low-voltage NOTE ­ High-frequency 2 Reference documents and the proof tracking indices of so/id IEC 60112:1979, Method for determining the comparative insulating rnateria/s under moist conditions IEC 60664-1:1992, /nsu/ation coordination Principles, requirements and tests for equipment within low-voltage systems - Part 1: 3 Clearances respect to that amplitude. For ms, Therefore, effective. This Breakdown of clearances usually occurs in less than one submicrosecond. With time scale, an a;c. voltage of power frequency has an essentially constant instance at 50 Hz, the amplitude remains within 99 YO of its peak value for 1 during the development leading to breakdown, the peak value of the voltage is normally results in identical a.c. (peak) and d.c. breakdown voltages. At much higher frequencies, a reduction of the voltage from its peak value and even polarity reversal have to be taken into account during the development of breakdown. This effect will result in an increase of the breakdown voltage. Up to now, the effect of the ions (which are usually positive) which are generated during inception of breakdown has not been considered. These ions are generated at the crest of the sine-wave and there is usually enough time for them to travel to the electrodes during the remaining part of that half wave. However, in large clearances or at high frequency, the polarity may be reversed before the ions have been extracted from the clearance. This will result in a distortion of the electrostatic field and will reduce the breakdown voltage. The average velocity of the ions is approximately 6 x 102 mls [1]*. At 50 Hz, the time interval between the crest and the zero crossing of the sine-wave is 5 ms, resulting in the ions moving approximately 300 cm. Therefore, at power frequency, this aspect will only be relevant for very large clearances. However, if the frequency is increased to the kHz range, this phenomenon will atso be relevant for small clearances. q The figures in square brackets refer to annex A (Bibliography) 1 IS 15382 (Part 4) :2003 (1997) IEC 60664-4 The superposition of both effects results in typical curves which exhibit a minimum breakdown voltage for a certain frequency. For clearances with homogeneous and approximately homogeneous field distribution, data is shown in figures 1 and 2 [2]. At 25 MHz, the breakdown voltage is nearly the same as at 50 Hz. Figure 2 shows that the clearance is a very important parameter with respect to this behaviour. With respect to the frequencies presently used, the breakdown voltage with increasing frequency is of greater up to several MHz, is described in more detail hereafter. For small clearances in N2 at atmospheric pressure, range with the initial interest. This frequency decrease of range, being breakdown characteristics as air, the reduction of the breakdown voltage may only be 10 Y., as shown in figure 3 [3]. However, for frequencies exceeding 1 MHz, the reduction also becomes effective for very small clearances less than 0,5 mm. For larger clearances there is a greater reduction in the breakdown voltage, as-shown in figure 4 [4]. As a conclusion, for homogeneous and approximately homogeneous conditions, the maximum reduction of the breakdown voltage with frequency is about 20 %. The critical frequency at which the reduction of the breakdown voltage occurs is approximately: which has similar where f~~i~ d is the critical megahertz; is the clearance frequency at which the reduction of the breakdown voltage occurs, in in millimetres. of homogeneous and approximately homogeneous clearances in with respect to frequency can be summarized by the following The insulating characteristics air at atmospheric pressure statements. ­ Above /Crit, the breakdown voltage becomes in breakdown voltage may be up to 20 O/O. lower with increasing frequency. The reduction ­ The breakdown voltage has its minimum at frequencies between 1 MHz and 5 MHz. With higher frequencies, the breakdown voltage becomes higher and may exceed the value at power frequency. approximately from the equation given. voltage is much more significant. This For inhomogeneous field conditions, fCrit is still obtained Above fcrit, the influence of frequency on the breakdown can be seen from figure 5 [5] for comparatively large clearances and a 30° point electrode in combination with a plane electrode of 15 cm diameter. The reduction of the breakdown voltage by the with respect to that at 50 Hz can be more than 50 ?40. The results are strongly influenced electrode configuration. The lowest breakdown voltages were measured with the plane electrode earthed. As a general rule, it is essential to have approximately homogeneous field conditions if there is high-frequency voltage stress. 2 IS 15382 (Part 4) :2003 (1997) IEC 60664-4 4 Creepage distances In IEC 60664-1, tracking is the only phenomenon taken into account for dimensioning of However, recent research [6] provides evidence that this does only creepage distances. apply for very severe environ.mental conditions, and if the materials used are not resistant to tracking (see EC 601 12). Under more favorable environmental conditions, tracking does not seem to be relevant for dimensioning. In this case, the flashover voltage across the surface of the insulating material is reduced by pollution and has to be taken into account for dimensioning [7]. It is not known whether tracking is influenced by the frequency of-the voltage. However, under conditions of severe pollution, or for materials having a low comparative tracking index, small dimensions are not possible, and a safety margin has to be provided. This safety margin may also al~ow for a possible influence of frequency on the withstand capability. For less pollution, the flashover voltage across the surface of the insulation seems to be relevant for dimensioning and a possible influence of frequency has to be considered. However, this influence may already be covered by the frequency dependence of the breakdown voltage of the associated clearance according to clause 3. Long-term influence of humidity is likely to change this situation. A significant reduction of the breakdown voltage -across insulation surfaces, especially for higher frequencies, occurs under such conditions. This is mainly a problem caused by water absorption within solid insulation, and this phenomenon is considered in clause 5. 5 Solid insulation Two failure mechanisms of solid insulation are normally relevant. One failure mechanism results from dielectric loss at high electric stress. Increased heating will occur, which may lead to thermal instability and thermal breakdown. This usually takes place within a few minutes and can be easily verified. Additionally, solid insulation can include gas gaps or voids, either caused by different layers of insulation, interfaces between insulating parts and conductive parts, or by imperfect manufacturing of the insulation material. In such small gaps, partial discharges are likely to cause eventual failure of solid insulation even if the dielectric stress is sufficiently low so as not to cause thermal breakdown. For solid insulation, the frequency dielectric loss for a given frequency of the voltage is a very important influencing is obtained from the following equation: Pv. where P" is the power dissipation; tan6x27cfx@x C factor. The tan 6 is the loss factor; f is the frequency; is the voltage across the solid insulation; arrangement. u c is the capacitance cd the insulation 3 IS 15382 (Part 4) :2003 (1 997) IEC 60664-4 Due to the dependence of the loss factor tan d on frequency, the influence of frequency on the dielectric loss may be lower or higher than can be expected from the apparent linear dependency. This results in a higher probability of thermal breakdown and a reduction of the short-time dielectric withstand capability. This phenomenon has been investigated on different insulating materials [8]. The most important results are shown in figure 6. For a frequency of 1 MHz, the short-time breakdown field strength may only be 10 ?!. of the power frequency value. The breakdown field strength does not seem to reach a lower limit even at frequencies as high as 100 MHz. The dielectric strength of solid insulation in general, and especially is further reduced by the influence of humidity and temperature. at high-frequency voltage, The influence of long-time storage on the breakdown field strength of solid insulation at highfrequency voltage under high humidity is shown in figure 7 [9]. The reduction of the breakdown field strength of mica-filled phenolic is extraordinarily high. This is a significant problem at power frequency, but is further aggravated with increasing frequency. The poor performance of mica-filled phenolic is caused by its comparatively high water absorption, which was found to Under the same conditions, the water be in the order of 1 7. by weight under such conditions. absorption of glass-silicone laminate was only 0,3 Y. by weight. The breakdown field strength of solid insulation is a function of the thickness of the material, and very thin films may have a breakdown field strength one order of magnitude higher than that of the 0,75 mm test specimen. This is shown in figure 8 [10]. With increasing frequency, there is a significant reduction of the values. At 1 MHz only approximately 10 ?'. of the 50 Hz values were found. At such high frequencies, the behaviour of thin films seems to be similar to that of specimens having approximately 1 mm thickness. The influence of the thickness of the film on the breakdown voltage can be seen in more detail in figure 9 [10]. There is some indication that the breakdown voltage of very thin films is slightly less affected by frequency, but even for 0,01 mm film, there is still a significant reduction. Figure 10 [11] shows that the breakdown field strength of solid insulation at all frequencies additionally reduced with increasing temperature. The influence of increased temperature the breakdown voltage of thin films is shown in figure 11 [10], which shows that the reduction breakdown voltage with increasing temperature is aggravated with increasing frequency. is on of So far, only short-time stress and thermal breakdown have been considered. For long-time stress, partial discharges have also to be taken into account [12]. Experience shows that, in particular, thin insulation used in low-voltage equipment cannot withstand these discharges for long periods. Therefore, partial discharges should not be maintained under steady-state conditions. Partial discharges are to be expected at a dielectric stress significantly lower than that causing thermal breakdown. Detailed results concerning the partial discharge characteristics at high-frequency voltage are only available for frequencies up to a few kHz [13, 14]. In that range, it has been established that the time to failure caused by partial discharges is inversely proportional to frequency. This relationship has been used for accelerated testing. Therefore, especially at higher frequencies, a reasonable lifetime cannot be expected when partial discharges occur. Detailed measurements have been made on - coated printed circuit boards. One of the test boards is shown in figure 12. A typical plot of thr partial discharge intensity (apparent charge q) is shown in figure 13 [15]. 4 IS 15382 (Part 4):2003 IEC 60664-4 ( 1997) For this type of test specimen, an increase of the apparent charge with increasing frequency is more likely to occur than a decrease. It has been established that at high frequency, the time to failure may only be in the order of minutes. Therefore, partial discharge testing at high frequency for such periods may be destructive. Additionally, voltage the partial discharge inception voltage As shown Ui and in figure the partial discharge extinction of the LJe may be influenced by frequency. 14 [15], some reduction partial discharge voltages with increasing frequency is to be expected for coated printed circuit boards. However, this characteristic seems to depend on the type of test specimen. As shown in figure 15 [15], the partial discharge voltages of optocouplers do not seem to be influenced by frequency. At high frequency, there seems to be even some tendency of a decrease of the apparent charge q. However, the combined effect of frequency and apparent charge as the source of failure is more onerous than at power frequency. 6 High-frequency The following testing with regard to frequency: and, in particular, for solid tests are relevant verification of the short-time dielectric strength for clearances insulation by an a.c. voltage test at high frequency; with regard to long-time electric under steady-state conditions. stress, verification that no partial discharges are maintained the present time, high-frequency test equipment is only available so that only components and small subassemblies can be tested. 6.1 High-frequency breakdown test frequency. with limited power output, This test is similar to the high-voltage test at power power HF test voltage scwrces are available. 6.1.1 Test method At present, no standard high- It has been -obsemed that the high-frequency withstand is influenced by equipment temperature and environmental conditions. The test should be performed under the most onerous conditions that may be encountered in service, including the temperature rise caused by normal operation of the equipment. 6.1.2 Test equipment For frequencies up to a few MHz, one way to generate the test voltage is by using a high-power oscillator in combination with an air-core transformer. An appropriate circuit is shown in figure 16 [10]. With this circuit, fixed frequencies from 100 kHz up to 10 MHz can be adjusted with an output power of 1,5 kW. Due to the high capacitive loading, both frequency and output voltage are influenced by the test specimen. In order to cover the whole frequency range from a few kHz to 1 Ml+z, a test circuit of a high-power amplifier and an HF resonance transformer can be used. The circuit in figure 17 [15], together with a partial discharge detection circuit. The frequency resonance transformers dependent on the number of secondary turns is shown in High-frequency operation requires a low number of secondary turns. In order to whole frequency range, several resonance transformers are required. consisting is shown range for figure 18. cover the 5 IS 15382 (Part 4) :2003 (1997) partial discharge test IEC 60664-4 6.2 High-frequency 6.2.1 Test method Due to the high risk of deterioration of the test specimen at high frequencies, the rate of voltage rise should be as high as possible without causing overshoot. In general, the noise level during high frequency partial discharge testing will be significantly higher than that occurring during power-frequency testing. The preliminary results obtained for optocouplers give some indication that the partial discharge voltages are not significantly influenced by frequency. if this could be verified on a more representative basis, a partial discharge test with power-frequency voltage could be sufficient to give enough information about the partial discha-rge characteristics of optocouplers at high frequency. For coated printed circuit boards, this is different, because both the partial discharge voltages and the partial discharge intensity are influenced by frequency. These aspects need furthe-r investigation with other test specimens. 6.2.2 Test equipment source The measurement of partial discharges is more difficult, because both the test voltage and the partial discharge measuring equipment are not readily available. However, this difficulty' `may be overcome by employing laboratory apparatus as shown in figure 17. The partial discharge detection is performed by digital integration with a digital storage oscilloscope of high sampling rate. With this test circuit, the data shown in figures 13 to 15 were Qbtained. IS 15382 (Part4) :2003 IEC 60664-4 ( 1997) 16 14 12 r 4 2 0 o I I 0" I + 50 Hz - + -0,88 MH; ­ + ­ 2,5 MHz --X-- 12 MHz +K -25 MHz I I 1 I 1 I I 1 I I I I I I I I I I 1 I I I I I I I I I I I I I II 1 2 d/mm~ 3 4 Figure 1- Breakdown at high frequency in air, homogeneous field [2] IS 15382 (Part 4):2003 IEC 60664-4 (1997) 0,5 LJ ` 1,5 A v 2,5 -- -- .3,5 -@- mm mm mm mm_ -.+ + ~4,0 1,0 mm 2,0 mm 3,0 mm mm_ x. b , a, > 0 10-2 1 1 111111 I i 111111 I I 1111 I I 111111 t 1 111111 1 I 111111 I I Illlu 10-1 10° 101 102 103 104 105 f/kHz+ Figure 2Broekdown at high frequency in air, homogeneous field [2] 8 IS 15382 (Part 4) :2003 ( 1997) IEC 60664-4 -1f ---- 11 I I 1 -o-c - + -2,4 MHz ­ X- -4,2 MHz + 6,6 MHz J I I I I I 1 I I 1 I I J 1 I I J I I 1 0.0 0.1 0.2 0.3 0.4 d/mm~ 0,5 05 . L 07 . 08 . Figure 3- Breekdown at high frequency in nitrogen, homogeneous field [3] 9 IS 15382 (Part 4):2003 IEC 60664-4 ( 1997) 18 16 -0-U+ --00,5 1,5 2,5 3,5 4;5 I mm mm mm mm mm A m ---X-- w -1,0 -2,0 3,0 -4,0 5,0 mm mm mm mm mm o -x A t t n 4 2 0 1 I I 11111 1 I 111111 I I 111111 i I 111111 I I 111111 i I Illlu 10-2 10-1 1(Y 101 102 103 104 f/kHz ~ Figure 4- Breakdown et high frequency in air, homogeneous field [4] IS 15382 (Part 4) :2003 IEC 60664-4 ( 1997) 1 * --)(-- + ~ I 50 Hz; point earthed 75 kHz; point earthed 50 Hz; plane earthed I 75 kHz; `plane earthed ,x 1I 1II IIi 1II o III 20 40 60 80 100 120 140 160 180 200 220 d/mm Figure 5- Breakdown et high frequency in air, inhomogeneous field [5] 11 IS 15382 (Part 4):2003 ( 1997) IEC 60664-4 100 80 60 40 20 n Ui . L w 4 2 1 0.8 0.6 0.4 0.2 U ---U + + .+ --0+' --X-- + + mica-filled phenolic, mould~fi polytetrafluorethylene polyethylene polystyrene forsterite ceramic dry-process porcelain glass-bonded mica glass glass-silicone laminate glass-melamine laminate paper-phenolic laminate ) .0-2 d= 0,75 mm 10-1 10° 101 f/kHz~ 102 103 104 105 Figure 6- Breakdown at high frequency, solid insulation [8] 12 IS 15382 (Part 4) :2003 ( 1997) IEC 60664-4 60 40 20 10 8 6 x >( 0.1 0.6 0.4 0.2 0.08 A 0.1 + + + ~ --)(-- + II 1 1111 1o-1 0.06 0.04 0.02 mi~-filled phenolic; d = 0,75 mm; new rni~-filled Phenok d = 0,75 mm; 180d/50% r.h. mi~~filled phenoliq d = 0,75 mm; 180cY1 00% r.h. 91ass-siliCOne laminate; d = 1,5 mm; new glass-silicone laminate; d = 1,5 mm; 180d/50% r.h. 91ass-silicone laminate; d = 1,5 mm; 180d/100% r.h. 0.01 I .0-2 ~ Figure 7- 1 I 111111 I I 111111 I I 111111 I I 111111 I I 11111 I I I 1111~ 102 103 104 105 1.OO 101 f/kHz+ Breekdown et high frequency, eolid ineuletion; conditioning at 50 "C [9] 13 IS 15382 (Pm-t 4) :2003 (1997) IEC 60664-4 10 8 6 4 \. I I I I I 1 2 t ~1 ~ o.8 ; o-b 5 0.4 -4 I cellulose-acetobutyr polycarbonate; 0,03 M cellutose-triacetate; 0,03 mm Cellulose-acetobutyrate; 0,06 mm polycarbonate; 0,06 mm cellulose-triacetate; 0,06 mm i --)(-- + 0.2 0.1 I I 11111I I 111111I 1111111I I 111111I I 1111111 I 1111/ 10-1 10° 101 102 103 104 f/kHz~ Figure 8- Breakdown at high frequency, insulating films [1O] 14 IS 15382 (Part 4):2003 IEC 60664-4 (1997) 40 A m A u ` 0,01 mm 0,02 mm ` ~ 20 x. . A v A v --x-- 0,05 mm_ 0,08 mm 0,10 mm 10 8 6 t I I I I I I I xl \\' 0.4 0.2 0.1 10-z 10-1 10° 101 102 103 104 f/kHz~ Figure 9- Breekdown et high frequency, polystyrene film et 20 "C [10] 15 IS 15382 (Part 4) :2003 (1 997) IEC 60664-4 100 80 60 40 -4= xW 20 ~ + ~ :8 ~6 s x iD4 10 I I I I I + + -'5°c 20°c 2 --X-- + loo"c 60"C 1 I I llllJ# I I 111111 I i 111111 1 I 111111 I I 111.1.jJ I I 111111 10-i 10° 101 102 I I IIIIJ 104 10-3 10-2 103 f/kHz+ Figure 10- Breakdown at high frequency, paper laminate (pertinax); temperature [11] 16 IS 15382 (Part 4) :2003 IEC 60664-4 ( 1997) i-o 8 6 4 2 t 0.4 + + -0- polystyrene; 0,08 mm; 25 "C polystyrene; 0,08 mm; 50 `C _ 0.2 .+ --X-- polystyrene; 0,08 mm; 80 "C polyethylene; 0,05 mm; 25 `C polyethylene; 0,05 mm; 50 "C 0.1 102 103 f/kHz~ 104 Figure 11- Breakdown at high frequency, insulating films; temperature 17 IS 15382 (Part 4) :2003 (1997) IEC 60664-4 0,12 mm 0,19 mrn 0,3-1 mm 0,57 0,12 mm 1 mm mm mm mm 1 1 ` 1 0,19 0,30 0,57 0,13 mm 0,22 0,30 rrtm 1 mm mm J 2 0,55 0,14 mm 0,19 mm 0.31 mm 0,56 7 3 mm 1 & 1 1- through 23- holes (interconnecting 45° 90° values are the of layers) conductors conductors The distance measured, smallest ones between adjacent actually being Figure 12- Layout of the test board 18 IS 153S2 (Part 4) :2003 IEC 60664-4 (1 997) 105+/ / /A\ \ 104 / / + / / ` / / / / / 103 x / / I g \ u- 102 \ \ \ / ~ ` ~ 101 / ­x-* conductors; 90° conductors; 45° through-holes I JLwuL_W 10-2 10-1 d= 0,3 mm 10° f/kHz+ 101 102 Plgure 13- Pertial diecherge et high frequency, coeted printed circuit board [15] 19 IS 15382 (Part 4):2003 IEC 60664-4 (1 997) 2.0 1.8 1.6 1.4 -\ \. 1.2 1.0 0.8 0.6 0.4 0.2 , \w/' \ 1 I L - X + + + - + --)(-- mndu~ms; 90°; Ui mnductors; 90°; Ue @nduaors; 45°; Ui conductors; 45"; Ue through-holes; l..Ji - through-holes; Ue I 0.0 10-2 1 I I I 11111 I I 1I 111~ 10-1 10° I I I 1 1111 I 1 1 101 102 f/kHz~ d= 0,2 mm Figure 14- Pertiai diecharga et high frequancy, coated printad circuit board [15] IS 15382 (Part 4):2003 IEC 60664-4 (1 997) 1.8 L 1.6 1.4 x­ -" --­­­­­I I I / ._.)(_ \ --1 _+ 700 L \ \ 1.2 Lo n --2 I I 0.8 \ \ \ \ 4 1-l I + 600 500 t u 400~ u300 I 0.6 I I d / I I 0.4 + 0.2 0.0 I u, ­X--ue *q -- 200 100 10-2 10° f/kHz~ ~() 101 102 Figure 15- Partiel diecherge et high frequency, optocoupier_[15] IS 15382 (Part 4):2003 IEC 60664-4 (1 997) Figure 16- Baaic circuit of a HF power oscillator (colpitt circuit) 22 IS 15382 (Part 4) :2003 JEC 60664-4 ( 1997) 3 / / 4 2 5 6 / -- k E E 4 B B -- -EIlf2 mF B p--( I . u s -- /11 1- HF generator and power amplifier, 2- HF resonance transformer 3 ­ test specimen 4 ­ coupling impedance 5678HF high-voltage probe screened cage digital storage oscilloscope impulse amplifier discharge f= 2 kHz ­ 500 kHz 9- conventional partial 10 ­ digital voltmeter 11 ­ analogue 12control oscilloscope computer detector Figure 17- HF partial discharge teat circuit 23 IS 15382 (Part 4) :2003 (1 997) IEC 60664-4 8 7 -.. . . . . . . . . . . . . . . . . . . . . . ,.. . ., .-. . . . . . . . . . . . .--" ---- . -. ---",- -- . . 4 ,.. . .. . . . . . . . . . . . . -. 3 ,--" -! --'-"," --- ;-- . . 2 !.. . . . 1 . . 0 200 250 300 350 400 450 500 550 600 650 700 750 f/kHz --F Number Number of primary turns A/l = 20; ~ -350, of secondary turns A12: s - 210, +-280, u -420, X- 560 Figure 18- Output voltage of HF resonance traneformere . 24 IS 15382 (Part 4) :2003 (1 997) IEC 60664-4 Annex A Bibliography [1] B. Ganger, E/ecfrica/ breakdown of gases Gottingen/Heidelberg 1953, pp. 422-450. F. Muller, E/ecfrica/ breakdown of air at very Elektrotechnik, vol. 28, pp. 341-348, 1934. (in German), Springer Verlag, Berlin/ [2] high frequency (in German), Archiv fur [3] A.W. Bright in Meek, Craggs, E/ectrica/ breakdown of gases, Chichester/New York/Brisbane/Toronto 1978, Chapter 8, pp. 696. H. Lassen, Frequency dependence of the breakdown fur Elektrotechnik, vol. 25, pp. 322-332, 1931. J. Kampschulte, Breakdown of air for a.c. voltage fur Elektrotechnik, vol. 24, pp. 525-552, 1930. 28A/1 08A/CDV: Amendment to creepage distance requirements. IEC 60664-1 vo/tage John Wiley & Sons, [4] in air (in German), Arch iv [5] of 50 to 100000 I-/z (in German), Archiv [6] ­ Revision of po//ution degrees and [7] F, Uhlemann, Evaluation of new dimensioning criteria Technische voltage equipment (in German), Dissertation, for creepage distances Hochschule Darmstadt, Electrical in low1990. [8] J.J. Chapman, L.J. Frisco, Dielectric pp. 136-143, 1954. strength of so/id insulation, manufacturing, [9] J.J. Chapman, L.J. Frisco, J.S. Smith, Trans., vol. 74, pp. 349-354, 1955. Dielectric failure of volume and surface types, AIEE [1 o] H. Suhr, Evaluation of the influencing factors on the breakdown voltage Technische Universitat Berlin, 1961. fi/ms (in German), Dissertation, P. Perlick, Frequency 10s Hertz (in German), dependence Dissertation, of thin insulating [11] of the breakdown vo/tage of so/ids in the range Technische Hochschule Berlin, 1934. components for O to [12] W. Pfeiffer, equipment T. Facklam, Partia/ discharge testing of (in German), ETZ, vol. 109, pp. 440-447, 1988. /ow-vo/tage [13] A. W ichmann, P. G ru newald, Lifetime investigations of high- vo/tage insulating systems with acceleration by increasing the frequency of the test vo/tage (in German), ETZ-A, VOI. 95, pp. 318-322, 1974. Y. Ikeda, T. Tanaka, Frequency acceleration endurance tests by a g/ass-covered e/ectrode VOI. 17, pp. 64-69, 1982. characteristics system, IEEE in internal discharge Trans. Electric, Insu 1., [14] [15] H. Rein hard, Evacuation of the insulating characteristics of solid insulation for frequencies up to 100 kHz within coated printed circuit boards, optocouplers and transformers (in German), Dissertation, Technische Hochschule, Darmstadt, 1990. (Continued from second cover) For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test, shall be rounded off in accordance with IS 2:1960 `Rules for rounding of numerical values (revised)'. The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. 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